Russia has reportedly moved military vehicles towards the city, which is within striking distance of North Korea.
The dramatic move, unconfirmed by the Russian government, was spotted by residents in the border city and posted on social media.
This comes as North Korea warned that they are prepared for all-out war with the US, while China pleads for the two powers to back down from escalation.
Since the emergence of the Vladivostok footage, fears have grown that North Korea could become the trigger for a conflict involving the US, China and Russia.
Both China and Russia consider North Korea as a necessary buffer state, which they need to keep stable for their own national security.
According to the reports, a military convoy of eight surface-to-air missiles, part of Russian Air Defence, were on the move.
The S400 anti-aircraft missiles were moved to Vladivostok, where Vladimir Putin already has a major navy base.
North Korea has warned the US not to take provocative action, after holding a military parade that showed off new intercontinental and submarine-launched ballistic missiles.
Officials from the despotic regime have said that the country will “hit back with nuclear attacks” if necessary.
There is mounting speculation that current leader Kim Jong-un will soon order a new nuclear test.
President Donald Trump has already pledged to remove the threat from the Korean peninsula.
China has pleaded for the US and North Korean to back down from the war-footing.
On Friday, China’s Foreign Minister Wang Yi warned that “conflict could break out at any moment”.
He said: “We call on all parties to refrain from provoking and threatening each other and not to let the situation get to an irreversible and unmanageable stage.”
Air China, owned by the Chinese government, decided to end its service between Beijing and Pyongyang, amid fears of an escalation.
This comes after a US aircraft carrier group continues to move towards the region.